Detainees walk in a line at a U.S. Customs and Border Protection processing facility June 18 in Brownsville, Texas.

The Basics of the Border Crisis: How Did We Get Here?

More than 52,000 unaccompanied children have crossed the U.S.-Mexico border since October. Here's a look at why it's happening and how authorities and communities are coping:

When did the crisis start?

The Department of Homeland Security said the uptick in unaccompanied minors crossing the border began last year but accelerated in the last few months. Since October, more than 52,000 children traveling without an adult were caught entering the United States through Mexico — double the number of the previous year and triple the number in 2011.

Where are the kids coming from?

About three-fourths of the children are from Central America: Honduras, Guatemala, El Salvador. The rest are from Mexico.

How do they get to the U.S.?

They travel by bus, train, car and raft to Mexico, often led by smugglers who charge up to $10,000 each, officials say. They then walk across the border and into the custody of U.S. agents. It's a punishing journey that leaves the children and teens vulnerable to abuse or sex trafficking. In June, the body of a 15-year-old Guatemalan boy was found in some brush at the border.

Why are so many coming now?

Families are sending their children to the U.S. to escape crime, gangs and poverty and to reunite with relatives who may already be on American soil. The surge appears to be rooted in rumors that a change in U.S. immigration policies means any child who crosses the border can stay.

"If she gets across she can stay here, that's what you hear," one Guatemalan mother, who is living in the U.S. illegally and sent for her teenage daughter, told the Associated Press last month. "Now they say that all children need to do is hand themselves over to the Border Patrol."

It's a myth. Children who arrived after 2007 are not eligible for deferred deportations or a proposed path to citizenship. "There are no 'permisos,' 'permits,' or free passes at the end," Homeland Security Secretary Jeh Johnson said.

Why doesn't the U.S. just send them back?

By law, unaccompanied children are transferred into the custody of the Department of Health and Human Services within 72 hours of their arrest. The next stop is temporary shelters — a network of 100 around the country that are over capacity — until authorities can find family or foster homes to take them while their cases play out in immigration court, a process that can take years.

While Mexican adults are often sent right back across the border, the women with children who come from Central America are being kept in family detention centers or let go with orders to return for a court date.

What happened in California?

Immigration authorities tried to bus undocumented women and children to Murrieta on July 1 to be processed. Dozens of protesters, saying they feared that the immigrants would be released into the local community, blocked the road and clashed with a smaller group that showed up to welcome the newcomers. The bus turned around, and it's unclear if more immigrants will be bused into Murrieta.

What's being done to solve the problem?

While immigration officials are scrambling to secure more shelter space for the new arrivals — Dallas County agreed this week to shelter 2,00 children if the feds foot the bill — the White House is focusing on prevention. The Obama Administration has earmarked millions for programs in Central American to receive repatriated citizens and crack down on crime and improve economic opportunity. The feds have also launched a Spanish language ad campaign to warn would-be immigrants to stay home.

Critics say the focus should be on beefing up border security. Texas Gov. Rick Perry told a congressional committee the kids should be deported immediately as a deterrent.